Evidence of quantum lateral confinement in side-gated resonant tunnelling diodes formed by patterned substrate regrowth

MBE regrowth on patterned np-GaAs wafers has been used to fabricate GaAs/AlGaAs double barrier resonant tunnel diodes with a side-gate in the plane of the quantum well. The physical diameters vary from 1 to 20 μm. For a nominally 1 μm diameter diode the peak current is reduced by more than 95% at a side-gate voltage of -2 V at 1.5 K, which we estimate corresponds to an active tunnel region diameter of 75 nm ± 10 nm. At high gate biases additional structure appears in the conductance data. Differential I-V measurements show a linear dependence of the spacing of subsidiary peaks on gate bias indicating lateral quantum confinement. © 1996 American Institute of Physics.

CARS在超音速燃烧研究中的应用

报道了氮、氧和水的Q支CARS谱以及氢的S(5)和S(6)纯转动CARS的测量结果,并用来确定超音速燃烧火焰中的温度及氧的浓度;用水的Q支CARS谱得到共振与非共振谱积分面积比随浓度的变化曲线.提出并发展的同时测量氢和氧的CARS谱新方法,为同时测量火焰温度和氢、氧浓度提供了一条途径,特别对不含氮的燃烧系统更具重要意义.

Multiplex CARS measurements in supersonic H-2/air combustion

H-2 and O-2 multiplex coherent anti-stokes Raman spectroscopy (CARS) employing a single dye laser has been explored to simultaneously determine the temperature and concentrations of H-2 and O-2 in a hydrogen-fueled supersonic combustor. Systematic calibrations were performed through a well-characterized H-2/air premixed flat-flame burner. In particular, temperature measurement was accomplished using the intensity ratio of the H-2 S(5) and S(6) rotational lines, whereas extraction of the H-2 and O-2 concentrations was obtained from the H-2 S(6) and O-2 Q-branch, respectively. Details of the calibration procedure and data reduction are discussed. Quantification of the supersonic mixing and combustion characteristics applying the present technique has been demonstrated to be feasible. The associated detection limits as well as possible improvements are also identified.

氢／空气预混平面火焰CARS温度测量

介绍了一套用于燃烧研究中对温度和成分浓度测量进行校准的氢／空气预混平面火焰燃烧４系统。采用氮ＣＡＲＳ技术对氢／空气预混平面火焰温度进行了系统的测量，包括不同当量比条件下的温度分布，温度的纵向和横向空间分布。结果表明，氮ＣＡＲＳ测温与氢／空气预混平面火焰的理论计算温度之间的误差为３.４％，而在燃烧炉表面上方１ｍｍ以上的空间属于火焰的温度均匀区，温度的不均匀性约为１.８％。

High temperature direct double side cooled inverter module for hybrid electric vehicle application

In this paper a novel approach to the design and fabrication of a high temperature inverter module for hybrid electrical vehicles is presented. Firstly, SiC power electronic devices are considered in place of the conventional Si devices. Use of SiC raises the maximum practical operating junction temperature to well over 200°C, giving much greater thermal headroom between the chips and the coolant. In the first fabrication, a SiC Schottky barrier diode (SBD) replaces the Si pin diode and is paired with a Si-IGBT. Secondly, double-sided cooling is employed, in which the semiconductor chips are sandwiched between two substrate tiles. The tiles provide electrical connections to the top and the bottom of the chips, thus replacing the conventional wire bonded interconnect. Each tile assembly supports two IGBTs and two SBDs in a half-bridge configuration. Both sides of the assembly are cooled directly using a high-performance liquid impingement system. Specific features of the design ensure that thermo-mechanical stresses are controlled so as to achieve long thermal cycling life. A prototype 10 kW inverter module is described incorporating three half-bridge sandwich assemblies, gate drives, dc-link capacitance and two heat-exchangers. This achieves a volumetric power density of 30W/cm3.

同时测量氢氧CARS光谱确定火焰温度和氢氧浓度的研究

利用YAG激光器和一台染料激光器同时测量了氢/空气预混平面火焰中氢氧CARS光谱。从氢的S(5)和S(6)支纯转动线的强度比获得火焰温度，并与由氮的CARS光谱得到的温度进行了实验校验。氢和氧的浓度分别由氢的S(6)支和氧的Q支光谱求得，并利用氢/空气预混平面火焰的局部热力学平衡计算对所得浓度进行了校验。温度的校验误差为4%，而氢氧浓度的校验误差分别为14%和12%。

Fabrication of self-aligned side gates to carbon nanotubes

We have fabricated self-aligned, side-gated suspended multi-walled carbon nanotubes (MWCNTs), with nanotube-to-gate spacing of less than 10 nm. Evaporated metal forms an island on a suspended MWCNT, the island and the nanotube act as a mask shielding the substrate, and lift-off then removes the metal island, leaving a set of self-aligned side gates. Al, Cr, Au, and Ti were investigated and the best results were obtained with Cr, at a yield of over 90%.

USED CARS测量对撞式扩散火焰的温度分布

介绍了用USED CARS技术测量对撞式甲烷/空气扩散火焰前滞止区和尾流区的温度分布剖面。在滞止区富甲烷观察到甲烷燃烧前的热解过程；尾流区温度高于滞止区温度，表明在滞止区有未完全燃烧的中间产物存在，在尾流区发现C_2及CH的光谱也证明了这一点。

同时测量氢和氧CARS谱的新方法

提出一种仅需一台染料激光器即可同时测量火焰中氢和氧的CARS谱的新方法。取带宽为120cm~(-1)，中心波长位于580.4nm的Stokes光束与532nm的泵浦光束相配合，同时测量氢扩散火焰中的氢和氧的CARS谱，用氢的S(6)和S(5)的积分强度比确定火焰中的温度并与氮的Q支CARS谱测量的温度和经过热损耗修正的热电偶测得的温度取得了相当好的一致结果。一次测出氢和氧的CARS谱，避免多次测量中参数的难以重复性，提高了以温度为参数来确定浓度的准确性。